We follow Grismer (2002) in treating Lampropeltis herrerae as a species distinct from L. zonata. The subspecies multifasciata, parvirubra, and pulchra were proposed as distinct species by Collins (1991), but no supporting data were presented, and this proposal has not been adopted by other herpetologists.

Rodriguez-Robles et al. (1999) studied phylogeography of L. zonata using mtDNA sequences and identified a basal split that corresponds to the southern (southern California and northern Baja California) and northern segments of the species' distribution. Within the northern clade, the authors identified two subclades, one that included populations from the central coast of California as well as the southern Sierra Nevada and a notheastern subclade that included populations north of San Francisco Bay and the majority of the Sierra Nevada. The northern clade apparently has undergone instances of range contraction, isolation, differentiation, and then expansion followed by secondary contact. "Recognition of the seven geographical races in L. zonata may not be appropriate, owing to their lack of diagnosibility using conventional criteria of pattern and scalation as well as lack of congruence with patterns of mtDNA differentiation" (Rodriguez-Robles et al. 1999).

Justification:
Listed as Least Concern in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.

The species' range extends from southwestern Oregon, south along coastal and interior mountains of California in the United States, to northern Baja California, Mexico (Sierra Juarez, Sierra San Pedro Martir), with isolated populations in south-central Washington and apparently also adjacent northern Oregon, from near sea level to about 2,750 m asl (9,000 feet) (Stebbins 2003).

This species is represented by at least several dozen occurrences or subpopulations (see map in Zweifel 1975). This snake is secretive and occurs in rough terrain that is often not easily accessible to humans; probably there are many more occurrences than are currently known. The total adult population size is unknown but probably exceeds 10,000 and may exceed 100,000 (conservatively assuming a density of at least one to 10 adults per sq. km in an area of occupancy of at least 20,000 sq. km). The collections of the California Academy of Sciences and the Museum of Vertebrate Zoology (University of California, Berkeley) include at least 185 specimens (Greene and Rodriguez-Robles 2003). Localized declines have occurred, but the overall level of decline is probably less than 25% compared to the historical situation. Its extent of occurrence, area of occupancy, number of subpopulations, and population size are probably relatively stable or declining at a rate of less than 10% over three generations or 10 years. In the southern part of its range, populations are restricted to higher elevations, and some of these could be small and threatened.

Some local populations probably have been reduced or eliminated as a result of habitat destruction associated with urbanization. However, much of the range of this snake is in fairly remote country that is not threatened by urbanization. Some populations have probably been detrimentally affected as a result of snake collection by reptile hobbyists and commercial collectors and by the damage collectors do to the microhabitats used by this snake (Grismer 2002, Ernst and Ernst 2003). This has impacted accessible populations (for example, along roads) in particular, but collectors also venture into remote areas for this species. Collectors have in particular impacted its microhabitat in the southern of its range, in southern California and in Baja California.

Grismer, L.L. 2002. Amphibians and Reptiles of Baja California, Including its Pacific Islands and the Islands in the Sea of Cortés. University of California Press, Berkeley and Los Angeles, California.

Stebbins, R.C. 2003. A Field Guide to Western Reptiles and Amphibians. Third Edition. Houghton Mifflin Company, Boston, Massachusetts.

Welsh, H.H. 1988. An ecogeographic analysis of the herpetofauna of the Sierra San Pedro Martir region, Baja California with a contribution to the biogeography of the Baja California herpetofauna. Proceedings of the California Academy of Science, 4th series 46: 1-72.